Such cutting inserts are usually of the replaceable kind and are releasably clamped between the clamping jaws of a tool holder. In order to allow for the face grooving operation which results in the formation of a circular face groove, it is known to use circularly curved clamping jaws so as to allow for their unhindered insertion during grooving into the circular groove. In addition, it is known to curve the flank surfaces of the insert in order to facilitate the unhindered insertion of the insert into the circular groove. The production of inserts with such curved flank surfaces, however, gives rise to considerable problems when using conventional moulding techniques and it has recently been proposed, as an alternative to curving the flank surfaces, to have planar flank surfaces which taper by amounts and directions such as to provide clearance between the flank surfaces and the side walls of the groove being cut.
A problem which arises with replaceable grooving cutting inserts in general, and face grooving cutting inserts in particular, is associated with the provision of the insert with a pair of opposite cutting edges. Thus, the provision of such cutting inserts with opposite cutting edges is clearly advantageous, seeing that it leads to a saving in cutting insert material and allows for the rapid indexing of the insert so that a fresh cutting edge is available for use when the opposite cutting edge has become dulled by use. The provision of cutting inserts with a pair of opposite cutting edges, however, will tend to limit the depth of the grooving cut, seeing that with grooving being effected by one cutting edge, any attempt to extend the depth of the cut so that the second, opposite cutting edge begins to penetrate this cut, results in this second, opposite edge becoming jammed within the circular groove.
There has been disclosed in the published European Patent Application No. 0 150 901, a double edged grooving insert designed for unlimited cutting depth, wherein a first cutting edge is located in a plane substantially at right angles to the second cutting edge. The production of such a grooving insert, especially when the cutting edges are to be provided with appropriate chip forming structures, gives rise to problems and requires the modification of normal moulding techniques.